Tribological properties of protic ionic liquid and functionalized copper oxide nanoparticles as additives to base oil

Abstract

The aim of the present study was to investigate a novel composite as lubricant additive for metal wear parts, composing of protic ionic liquid and functionalized copper oxide nanoparticle composite. A simple and an easy-to-modify synthesis method for the preparation of thiol covered copper oxide nanoparticles was developed. A long process of optimization of reaction parameters was carried out that resulted in preparing non-agglomerated oil dispersible copper oxide nanoparticles with an estimated average diameter of 60 nanometers based on SEM measurements. Novel protic ionic liquid, which dissolves in oil was synthesized. Lubricant tribological experiments with the standardized four-ball-method were conducted with 15 kg. The addition of 3% ionic liquid and 0.5% copper oxide nanoparticles to base oil reduced the wear up to 35% compared to base oil without any additives, while 1% of protic IL reduced wear up to 47%. In addition, the novel type lubricant additive has many advantages and can also widen the range of applications, e.g. wider temperature range and preserved functionality at harsh conditions where oil-based lubricants fail.